But Mr. Santamaría had been brought into the United States from Mexico as a baby. He'd been undocumented his entire life, and the vulnerability of an uncertain future weighed heavily on him.

Late in the evening on his graduation day, May 31, 2011, he took an irreversible step. He self-deported.

Santamaría's experience speaks to some of the various moral and legal issues Congress is now grappling with as it considers a possible legalization for 11 million undocumented immigrants.

"I always knew it was going to happen, eventually," he says of his choice to leave the US. "That realization came early during senior year. I submitted applications to colleges and to different financial aid funds, with the knowledge that I would be going to Tijuana after the year was done."

He didn't want to invest himself in an adult life that could be threatened, at any moment, by deportation.

His family initially questioned his decision. His mother, a green-card holder, had already moved back to Tijuana during Santamaría's junior year, because of the lower cost of living there.

Santamaría's two younger sisters also lived in Mexico. Being apart from them was hard, as was living with his grandmother.

"My high school always seemed to be the only place where I really belonged," he says. "Ambition drove people there and drove me as well. I wanted to be someone…. However, I thought to myself, 'I can stay [in the US] and be someone…. But I will not be able to drive, to go to college without amassing huge debt, and to do a litany of things that might seem insignificant to others but meant the world to me.' "

Santamaría's former college counselor, Emmi Harward, helped him defer acceptance to Fordham. The gap year came and went quickly. Today he's working in a Tijuana call center, helping frustrated Americans deal with cellphone issues.

His mother worries he'll regret moving back to Mexico.

Yet he doesn't think so – despite the fact that in June 2012, President Obama signed the Deferred Action for Childhood Arrivals (DACA) memorandum into law. It offers legal status to those who have been brought illegally to the US as children, like Santamaría. He would have qualified, meaning he could have become a naturalized US citizen if he'd remained in San Diego.

And now Congress is considering an amnesty that would offer legalization to more than 11 million undocumented immigrants.

Santamaría says he was trying to do the right thing by following the rules.

"I've always said that there is a proper way to do things for a reason," he says. "I am the most indecisive person you will meet, yet this decision was one of the least difficult."

He does admit, however, that "I now have a real sense as to why there is so much opposition to legalization.

"Let's say I start the process tomorrow through a family member to gain documentation, and then tomorrow Congress passes an IRCA 2.0 that legalizes people in the US and would have legalized me," he posits, referring to the federal Immigration Reform and Control Act of 1986 that offered amnesty to 3 million illegal immigrants living in the US.

"Yes, it would feel like a slight. After all, I did the 'right' thing…. And yet now, I am the 'fool' who decided to leave and follow the correct procedural avenues instead of staying undocumented, living in the shadows."

But, he says, "I was not going to stay and wait around for legislators to pass a bill. I followed US politics too much to wait for that."

Eventually, the 19-year-old believes, he'll return to the US – but with authorization. In the meantime, Santamaría dreams of becoming a journalist, and is steadfastly hunting for internship opportunities here in this Mexican border city.

But in doing so, he faces yet another hurdle: He's not fluent in Spanish.